A method of inserting an undulating winding into an alternator stator. The method comprises the following steps consisting of shaping each phase winding into a succession of crenels comprising two lateral branches which are intended to be attached at a position for reception in a slot, positioning the windings on an insertion tool and inserting the turns into the slots of the stator in the reverse order to the winding order. The windings are wound around the insertion tool simultaneously, and the turns that succeed one another in a determined winding order belong alternatively to different windings.